nostr:npub1hykucplphuhelaxutcw4jw3vuu7gcg42czhqmk7jhchs8vdga4fsj73p33 You are probably already aware of this; but if you are not, the character limit is defined by the instance. 

For example, I believe pleroma.social has 5,000 instead of default of 500. 

Mastodon.de has 4,000 as their character limit. 

Unfortunately there is no easy or builtin migration functionality that I'm aware of. 

But I don't mind the method you are using, just thought it might save you time.